#include "Mystdio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>

#define FILE_MODE 0666

// w a r
_FILE* _fopen(const char* filename, const char* flag)
{
    assert(filename);
    assert(flag);
    int f = 0;
    int fd = -1;
    if (strcmp(flag, "w") == 0)
    {
        f = O_CREAT|O_WRONLY|O_TRUNC;
        fd = open(filename, f, FILE_MODE);
    }
    else if (strcmp(flag, "a") == 0)
    {
        f = O_CREAT|O_WRONLY|O_APPEND;
        fd = open(filename, f, FILE_MODE);
    }
    else if (strcmp(flag, "r") == 0)
    {
        f = O_RDONLY;
        fd = open(filename, f);
    }
    else return NULL;
    
    if (fd < 0) return NULL;
    _FILE* fp = (_FILE*)malloc(sizeof(_FILE));
    if (fp == NULL) return NULL;
    fp->fileno = fd; 
    fp->flag = FLUSH_LINE;
    fp->out_pos = 0;
    return fp;
}

int _fwrite(_FILE* fp, const char* str, int len)
{
    memcpy(fp->outbuffer + fp->out_pos, str, len); // 没有做异常处理，也不考虑局部问题
    fp->out_pos += len;
    if (fp->flag & FLUSH_NOW)
    {
        write(fp->fileno, fp->outbuffer, fp->out_pos);
        fp->out_pos = 0;
    }
    else if (fp->flag & FLUSH_LINE)
    {
        if (fp->outbuffer[fp->out_pos - 1] == '\n')
        {
            write(fp->fileno, fp->outbuffer, fp->out_pos);
            fp->out_pos = 0;
        }
    }
    else if (fp->flag & FLUSH_ALL)
    {
        if (fp->out_pos == SIZE)
        {
            write(fp->fileno, fp->outbuffer, fp->out_pos);
            fp->out_pos = 0;
        }
    }
    return len;
}

void _fflush(_FILE* fp)
{
    if (fp->out_pos > 0)
    {
        write(fp->fileno, fp->outbuffer, fp->out_pos);
        fp->out_pos = 0;
    }
}

void _fclose(_FILE* fp)
{
    if (fp == NULL) return;
    _fflush(fp);
    close(fp->fileno);
    free(fp);
}
